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31.
32.
Oxovanadium(IV), copper(II) or cobalt(II) acetylacetone complexes immobilized on amino‐functionalized CMK‐3 for the aerobic epoxidation of styrene
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Xiufang Wang Shujie Wu Zhifang Li Xiaoyuan Yang Jing Hu Qisheng Huo Jingqi Guan Qiubin Kan 《应用有机金属化学》2015,29(10):698-706
Oxovanadium(IV), copper(II) and cobalt(II) acetylacetone complexes have been grafted onto amino‐modified CMK‐3‐O (VO‐NH2‐CMK‐3, Cu‐NH2‐CMK‐3 and Co‐NH2‐CMK‐3,respectively) and the materials thus prepared were used as heterogeneous catalysts for the aerobic oxidation of styrene. X‐ray diffraction, nitrogen adsorption–desorption and transmission electron microscopy measurements confirmed the structural integrity of the mesoporous hosts, and spectroscopic characterization techniques (Fourier transform infrared, X‐ray photoelectron, Raman) and thermogravimetry confirmed the ligands and the successful anchoring of the acetylacetone complexes to the modified mesoporous support. VO‐NH2‐CMK‐3 displayed a relatively good catalytic performance with 94.6% of styrene conversion using air as oxidant, while Cu‐NH2‐CMK‐3 gave 99.6% of styrene conversion using tert‐butyl hydroperoxide as oxidant. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
33.
We analytically and numerically study a 1 D tight-binding model with tunable incommensurate potentials.We utilize the self-dual relation to obtain the critical energy,namely,the mobility edge.Interestingly,we analytically demonstrate that this critical energy is a constant independent of strength of potentials.Then we numerically verify the analytical results by analyzing the spatial distributions of wave functions,the inverse participation rate and the multifractal theory.All numerical results are in excellent agreement with the analytical results.Finally,we give a brief discussion on the possible experimental observation of the invariable mobility edge in the system of ultracold atoms in optical lattices. 相似文献
34.
通过改变金属中心和配体官能团,合成了4个MIL-53系列金属有机骨架化合物NH2-MIL-53(Sc),NH2-MIL-53(Al),MIL-53(Sc)和NO2-MIL-53(Sc);研究了它们在合成α-氨基腈的Strecker反应中的催化性能.结果表明,NH2-MIL-53(Sc)对于Strecker反应具有优异的催化性能,并具有可重复使用性.通过对比NH2-MIL-53(Sc)和NH2-MIL-53(Al)的催化性能,分析了金属离子半径和金属中心不饱和配位点对Strecker反应的影响.通过对比NH2-MIL-53(Sc)与MIL-53(Sc)的催化性能,证明了作为路易斯碱中心的氨基可通过与路易斯酸中心的协同作用,有效促进Strecker反应的进行.通过对比NO2-MIL-53(Sc)与MIL-53(Sc)的催化性能,认为催化剂结构上的硝基对于Strecker反应的进行具有重要影响.最后,通过对比NH2-MIL-53(Sc)、硝酸钪和2-氨基对苯二甲酸(ATA)配体对催化性能的影响,总结出催化剂在纳米尺度的孔道结构是提高Strecker反应选择性的关键因素. 相似文献
35.
Dioxomolybdenum(VI) complex covalently attached to amino‐modified graphene oxide: heterogeneous catalyst for the epoxidation of alkenes
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Zhifang Li Shujie Wu Dafang Zheng Jiayin Liu Heng Liu Haiming Lu Qisheng Huo Jingqi Guan Qiubin Kan 《应用有机金属化学》2014,28(5):317-323
Transition metal salen complex MoO2–salen was successfully tethered onto amino‐functionalized graphene oxide (designated as MoO2–salen–GO), which was tested in the epoxidation of various alkenes using tert‐butylhydroperoxide or H2O2 as oxidant. Characterization results showed that dioxomolybdenum(VI) complex was successfully grafted onto the amino‐functionalized graphene oxide and the structure of the graphene oxide was well preserved after several stepwise synthesis procedures. Catalytic tests showed that heterogeneous catalyst MoO2–salen–GO was more active than its homogeneous analogue MoO2–salen in the epoxidation of cyclooctene due to site isolation. In addition, the MoO2–salen–GO catalyst could be reused three times without significant loss of activity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
36.
Enhanced nonisothermal crystallization of a series of poly(butylene succinate‐co‐terephthalate) biopolyesters by poly(vinyl butyral)
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Biao Yang Shujie Zhu Yi Luo Jijun Huang 《Journal of Polymer Science.Polymer Physics》2017,55(8):658-672
Enhanced nonisothermal crystallization of a series of poly(butylene succinate‐co‐terephthalate) (PBST) by poly(vinyl butyral) (PVB) as a macromolecular nucleating agent has been examined systematically with various techniques and theoretical modeling. The role of PVB depends strongly on the butylene terephthalate content, PVB content, and cooling rate. The (0.3–0.7 wt %) PVB reduces the spherulitic size, but considerably increases the peak temperature of crystallization, for example, by 28 °C for the PBST with 50 mol % terephthalic acid. The effects of PVB are believed to stem from its unique molecular structure. Both the hydroxyl and butyral groups of PVB may synergistically participate in nucleating PBSTs for crystallization because of favorable secondary interaction and affinity of butyral groups with butylene succinate units of PBSTs. Only the Tobin model suffices to describe the nonisothermal crystallization kinetics, while the modified Avrami model is suitable for limited crystallinity. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 658–672 相似文献
37.
Gaoke Zhang Shujie Yu Yanqing Yang Wei Jiang Shuiming Zhang Baibiao Huang 《Journal of Crystal Growth》2010,312(11):1866-1874
ZnMoO4 with a rhombus sheet or flower-like structure, α-ZnMoO4 and needle-like ZnMoO4·0.8 H2O were successfully synthesized by simple hydrothermal crystallization processes with citric acid. ZnMoO4·0.8 H2O was easily synthesized in a shorter reaction time (2 h) at a higher reactant concentration. It gradually transformed into ZnMoO4 with a monoclinic wolframite tungstate structure with an increased reaction time, and pure ZnMoO4 was obtained with a longer reaction time (8 h). Citric acid (CA) played an important role in controlling the morphology of the as-obtained molybdates. The α-ZnMoO4 and ZnMoO4 were synthesized by heating ZnMoO4·0.8 H2O at 130 °C for 4 h and 8 h, respectively, under hydrothermal conditions. With transforming of ZnMoO4·0.8 H2O to α-ZnMoO4 and further to ZnMoO4, the needle-like crystals gradually disappeared and were transformed into crystals with rhombus sheet morphology and then further to pentacle or flower-like crystals that can be ascribed to continuous splitting and growing of the rhombus sheets. 相似文献
38.
In this paper we study the periodic boundary problem: −u″−u+g(u)=h(t),u(0)=u(2π),u′(0)=u′(2π) with periodic nonlinearity g. We proved that the problem has infinite solutions. The method we used is a variational reduction method of T. Bartsch and S.J. Li. 相似文献
39.
40.
Wenjia Duan Qi Yue Ying Liu Yunfei Zhang Qinghua Guo Cong Wang Shujie Yin Dandan Fan Wenjing Xu Jiexian Zhuang Jiachao Gong Xinwei Li Ruimin Huang Liang Chen Silvio Aime Zhongliang Wang Jianfeng Feng Ying Mao Xiao-Yong Zhang Cong Li 《Chemical science》2020,11(17):4397
Surgery remains the mainstay for most solid tumor treatments. However, surgeons face challenges in intra-operatively identifying invasive tumor margins due to their infiltrative nature. Incomplete excision usually leads to early recurrence, while aggressive resection may injure adjacent functional tissues. Herein, we report a pH responsive ratiometric surface-enhanced Raman scattering (SERRS) probe that determined physiological pHs with a high sensitivity and tissue penetration depth via an innovative mechanism named spatial orientation induced intramolecular energy transfer (SOIET). Due to the positive correlation between tumor acidity and malignancy, an acidic margin-guided surgery strategy was implemented in live animal models by intra-operatively assessing tissue pH/malignancy of the suspicious tissues in tumor cutting edges. This surgery remarkably extended the survival of animal models and minimized their post-surgical complications, showing promise in precisely identifying invasive tumor boundaries and achieving a balance between maximum tumor debulking and minimal functional impairment.A novel pH ratiometrically responsive surface-enhanced resonance Raman scattering (SERRS) probe was developed for tumor acidic margin delineation and image-guided surgery. 相似文献